Dust collector



(uct-19, 194s.

L. LEE

DUST COLLECTOR 2 Sheets-Sheet 1 Filed Aug. '7, 1947 FIG.2

INVENTOR LEONARD LEE Y IME/150mm ATTORNEYS Oct. 19, 1948. f LEE 2,451,755

' DUST coLLEc'roR Filed Aug. 7, 1947 v2-SheetsSheet 2 INVENTOR LEONARD'LEE Patented Oct. 19, 1948 DUST COLLECTOR Leonard Lee, Glasgow,

James Howden & Company Limited, Glasgow, Scotland, a British company Application August 7, 1947, Serial No. 766,943 In Great Britain November 4, 1946 This invention relates to improvements in multi-cell dust collectorsl In a multi-cell dust collector comprising a number of cells associated with a collecting hopper, in which the dust is separated from the carrying medium by centrifugal action or by other means of separation, it is convenient and usual to have one air or gas inlet chamber and one air or gas outlet chamber communicating with all the cells. In some cases there may be more than one inlet chamber and one outlet chamber, it may be quite separate, or possibly provided by the use or division plates or walls; but in all cases one inlet chamber or section of an inlet chamber and one outlet chamber` or section of an outlet chamber communicate with a number of cells. Space limitations do not permit these chambers to be of large dimensions such that they are plenum chambers without appreciable air or gas flow, and it is usual to have an air or gas velocity of the order of 2() to 40 ft./sec. in the inlet and the outlet chambers. There are, therefore, frictional losses in the inlet and the outlet chambers which are not always equal and there is also in the inlet chamber, but not in the outlet chamber. a change from kinetic energy to static pressure. The result is a difference in the diiierential pressure between the inlet and the outlet chambers at the extreme ends of the collector which is caused by the difference in the Variation of static pressure in the inlet and the outlet chambers. This inequality in the differential pressures varies approximately at an even rate.

The static pressures in the individual cells are iniiuenced by the static pressures in the inlet and outlet chambers at the points at which each individual cell communicates with the inlet and the outlet, and consequently the static pressure at the bottom part of the individual cells varies from cell to cell with the result that there is interow of air or gas between the cells which is detrimental to the eiiiciency of dust collection.

According to the invention I introduce a pressure equalising system which sets up a depression in the hopper whereby interflow between the cells is prevented and the overall efficiency of dust collection is improved.

`With this object a quantity of air or gas is caused to how from the hopper, and I have found that for the system to operate most satisfactorily this quantity should be Very small compared with the quantity of air or gas flowing to the collector, being of the order of 3% to 5% of the total air or gas flow. I have also found that the best position in the hopper at which a depression is set up 3 claims. (el. 18s-s3) Scotland, assignor to by the pressure equalising system is nearest to the inlet. The means used for setting up the depression may consist of a small fan which discharges in the main outlet duct, and any dust drawn from the hopper is separated by a small auxiliary collector.

The invention is illustrated in the accompanying diagrammatic drawings in which Fig. l is a side elevation and Fig. 2 a plan view of a dust collector; Fig. 3 is an elevation of a modification; Figs. 4, 5 and 6 are fragmentary detail views drawn to a larger scale.

The dust collector shown in Figs. 1 and 2 is of the reverse low type and comprises a plurality of cells Hl wherein dust is separated from gas by centrifugal action. I I denotes the dusty gas inlet, l2 the clean gas outlet, and i3 the dust-collecting hopper.

In order to set up a depression in the hopper It there is provided a pressure equalising system including two ducts I4 leading from points I5 located near the inlet, to a small independent separator III. I'I denotes a small fan of which the suction is connected by a duct I8 to the outlet of the separator I and of which the discharge is connected by a duct I9 to the clean gas outlet I2. 20 denotes a regulating ldamper tted to the duct I8.

rIhe modification shown in Fig. 3 comprises a straight flow collector having a dusty gas inlet 2l, a clean gas outlet 22, and a hopper 23. The small fan and associated collector are indicated at 24, 25, respectively.

The cells may have inlet varies 26 as shown in Fig. 4, or tangential inlets 21 as shown in Fig. 5, or twin tangential inlets 28 as shown in Fig. 6.

In the case of casings or hoppers which are made up of a number of compartments, as in large collectors, a depression point may be applied to each compartment.

As will be understood, the invention may be applied to:

(a.) Dust collectors employing centrifugal action and comprising a number of -cells operating in parallel and enclosed in a common dust hopper, as in Figs. 1 and 2.

(b) Dust collectors as in (a) in which the axes of the cells are vertical, or horizontal, or inclined.

(c) Dust collectors as in (a) employing reverse flow -or straight ilow. y

(d) Dust collectors as in (a) as applied to boilers and cement kilns, in which dust is extracted from flue gases, and to similar installaduit for supplying dusty gas to the structure andi arranged to distribute dusty gas to the separator cells, a clean gas outlet conduit connected into said structure and arranged to receive clean gasV from each of the separator cells, an independent dust separator exterior to said structure, at least one conduit 4between said independent separator and a point of said structure adjacent to the position of the inlet conduit and arranged to receive gas discharged from the separator cells into the hopper from a -position above the collected dust in thehopper, a gas circulating fan, and conduits connecting the fan with said independent separator and with the clean gas outlet conduit, the fan and the conduits associated therewith being arranged to draw gas from the hopper to the independent separator and to draw clean gas from the independent separator and discharge it into the cleanv gas outlet conduit.

2. A multi-cell dust collector as claimed in claim 1 characterized by. including a damper interposed in the conduit between the independent separator and the hopper for regulating the gas flow in this conduit and controlling the depression set up in the hopper.

3. In a multi-cell dust collector having a structure including a, hopper for the reception of and collection of separated dust. a plurality 4 of dust separator cells Within the structure and mounted for the discharge of separated dust directly into the hopper, a dusty gas inlet conduit for supplying dusty gas to the structure and arranged to distribute dusty gas to the separator cells for the separation of dust therefrom, a cleanY gas outletconduit connected; into said structure and arranged to receive clean gas from' each of the separator cells, a pressure equalizing system associated with said structure for setting up a depression in the hopper and thereby preventl -interow of gas between the separator cells comprising an independent dust separator, at least oneconduit between said independent separator and` the part of said structure adjacent to. the position of the inlet conduit, the said one conduit being arranged to receive gas discharged from the separator cells into the hopper from a position above the collected dust in the hopper,

a gas circulating fan, a vconduit connecting the fan with said independent separator, and a conduit connecting the fan with the clean gas outlet conduit, the fanand the conduits connected thereto being arranged to draw gas from the hopper to the independent separator and to draw clean gas from: the independent separator and discharge it into the clean gas outlet conduit. LEONARD LEE.

REFERENCES CITED The following references are of record inthe le of this patent:

UNITED STATES PATENTS Number Name Date 1,930,806 Horne et al Oct. 17, 1933 2,188,206 Pfeffer er a1 Jan. 23, 1940v 

